//
// Created by 沃灵宗 on 2020/4/9.
//

/*
 *
 * Copyright 2015, Google Inc.
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 *
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 * modification, are permitted provided that the following conditions are
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 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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#include <iostream>
#include <memory>
#include <string>

#include <grpc++/grpc++.h>
#include <grpc/support/log.h>

#include "stub/helloworld.grpc.pb.h"

using grpc::Channel;
using grpc::ClientAsyncResponseReader;
using grpc::ClientContext;
using grpc::CompletionQueue;
using grpc::Status;
using helloworld::HelloRequest;
using helloworld::HelloReply;
using helloworld::Greeter;

class GreeterClient {
public:
    explicit GreeterClient(std::shared_ptr<Channel> channel)
            : stub_(Greeter::NewStub(channel)) {}

    // Assembles the client's payload, sends it and presents the response back
    // from the server.
    std::string SayHello(const std::string& user, int timeout_ms) {
        // Data we are sending to the server.
        HelloRequest request;
        request.set_name(user);

        // Container for the data we expect from the server.
        HelloReply reply;

        // Context for the client. It could be used to convey extra information to
        // the server and/or tweak certain RPC behaviors.
        ClientContext context;

        auto deadline = std::chrono::system_clock::now()
                        + std::chrono::milliseconds(timeout_ms);
        context.set_deadline(deadline);

        // The producer-consumer queue we use to communicate asynchronously with the
        // gRPC runtime.
        CompletionQueue cq;

        // Storage for the status of the RPC upon completion.
        Status status;

        // stub_->AsyncSayHello() performs the RPC call, returning an instance we
        // store in "rpc". Because we are using the asynchronous API, we need to
        // hold on to the "rpc" instance in order to get updates on the ongoing RPC.
        std::unique_ptr<ClientAsyncResponseReader<HelloReply> > rpc(
                stub_->AsyncSayHello(&context, request, &cq));

        // Request that, upon completion of the RPC, "reply" be updated with the
        // server's response; "status" with the indication of whether the operation
        // was successful. Tag the request with the integer 1.
        rpc->Finish(&reply, &status, (void*)1);
        void* got_tag;
        bool ok = false;
        // Block until the next result is available in the completion queue "cq".
        // The return value of Next should always be checked. This return value
        // tells us whether there is any kind of event or the cq_ is shutting down.
        GPR_ASSERT(cq.Next(&got_tag, &ok));

        // Verify that the result from "cq" corresponds, by its tag, our previous
        // request.
        GPR_ASSERT(got_tag == (void*)1);
        // ... and that the request was completed successfully. Note that "ok"
        // corresponds solely to the request for updates introduced by Finish().
        GPR_ASSERT(ok);

        // Act upon its status.
        std::string message_returned;
        switch (status.error_code()) {
            case grpc::StatusCode::OK:
                message_returned = reply.message();
                break;
            case grpc::StatusCode::DEADLINE_EXCEEDED:
                message_returned = "Server is busy.";
                break;
            default:
                message_returned = "RPC failed";
                break;
        }
        return message_returned;
    }

private:
    // Out of the passed in Channel comes the stub, stored here, our view of the
    // server's exposed services.
    std::unique_ptr<Greeter::Stub> stub_;
};

void RunAsyncClient(const char *endpoint, int timeout_ms) {
    std::string destination(endpoint ? endpoint : "localhost:50051");
    // Instantiate the client. It requires a channel, out of which the actual RPCs
    // are created. This channel models a connection to an endpoint (in this case,
    // localhost at port 50051). We indicate that the channel isn't authenticated
    // (use of InsecureChannelCredentials()).
    GreeterClient greeter(grpc::CreateChannel(
            destination, grpc::InsecureChannelCredentials()));
    std::string user("world");
    std::string reply = greeter.SayHello(user, timeout_ms);  // The actual RPC call!
    std::cout << "Greeter received: " << reply << std::endl;
}